Red Squirrels, the tree squirrel encountered in Edmonton, are small: up to 250 g. The Eastern Gray Squirrel can be as large as 700 g and also comes in an all-black form. Its natural range ends on the eastern side of the Great Plains, but populations have been introduced to places like Calgary and Vancouver. The Eastern Gray Squirrels in Calgary are the black form.
I learned that the name woodchuck is likely derived from the Algonquian name for this animal, wejack. It is also called a groundhog, but is not to be confused with a prairie dog, nor is it a ground squirrel, nor a gopher (which is in an entirely different rodent family) -- the woodchuck is actually a kind of marmot. Woodchucks can weigh up to 5.4 kg. The hoary marmot can be as large as 9.1 kg.
At the other end of the size scale are the chipmunks. The Least Chipmunk, which is the most common around these parts, weighs between 28 and 50 gm. Unlike other members of the squirrel family, the female chipmunk is larger and stronger than the male of the species. Most chipmunks don't put on a layer of fat before hibernating, so they have to wake up frequently to eat during the winter.